I. Field of the Invention
The present invention relates to novel tetrahydroisoquinoline derivatives, process for producing the same and a use thereof as a fungicide. The present invention also relates to novel tetrahydroisoquinolone derivatives which may be used as intermediates of the tetrahydroisoquinoline derivatives of the present invention and of other agricultural chemicals and drugs.
II. Description of the Related Art
Fungicides are indispensable in agriculture to prevent plant diseases and to increase the yield of the agricultural products. A number of agricultural fungicides are now used. However, some of them have poor fungicidal activities and some of them have restrictions on their use because of their toxicities to environment. Further, when the same or similar fungicides are used for a long time, pathogenic plant fungi which are resistant to the fungicides are generated, so that the effects of the fungicides are reduced. Thus, a fungicide with sufficient fungicidal activity, which is free from the problems on the pollution of environment and on the emergence of drug-resistant fungi is demanded.
Tetrahydroisoquinoline skeleton is contained in the benzophenanetrizine alkaloids and various physiological activities thereof including anti-cancer activity and anti-viral activity are known (e.g., J. Are. Chem. Soc. 1983, 105, 2873; J. Org. Chem. 1978, 43, 286; and J. Chem. Soc. (C) 1970, 2578; EP-A-0025598). However, the present inventors found novel tetrahydroisoquinoline derivatives having fungicidal activities.